SpaceX Recovery Techniques
David Spain
for Falcon booster recovery? Let's assume they are bringing down the entire
1st stage on chutes and using the [nearly] empty tanks for buoyancy.
Some simple questions to start:
1) Do the fuel tanks remain pressurized after engine off? And if so, what are
they pressurized with? The LOX tank is easy, what about the RP1 tank? How much
is left in the tanks after engine off? (If I had the time today, I'd try to do
some buoyancy calculations based on what I could glean from the SpaceX website.)
2) Assuming the heavy engine end is under water, is there a flotation collar
deployed around the top of the stage to hold it stable in the water?
3) Does the stage deploy a dye in the water to mark its position?
4) A ship-borne crane employed to lift the stage from the water? End first?
Side First?
5) How are the Merlin engines made to be sea-water proof? Would keeping them
pressurized with O2 only be a good idea to keep out the seawater? Or would
that likely cause the engines to ice over? Of course ice over of the engines
would improve overall buoyancy and help keep liquid seawater out. Interesting.
Jeff Findley
In article <XOadnQU4hZlkzFDQ...@giganews.com>, nospam@
127.0.0.1 says...
>
> So can anyone shed some light on the technology SpaceX is proposing to employ
> for Falcon booster recovery? Let's assume they are bringing down the entire
> 1st stage on chutes and using the [nearly] empty tanks for buoyancy.
>
> Some simple questions to start:
>
> 1) Do the fuel tanks remain pressurized after engine off? And if so, what are
> they pressurized with? The LOX tank is easy, what about the RP1 tank? How much
> is left in the tanks after engine off? (If I had the time today, I'd try to do
> some buoyancy calculations based on what I could glean from the SpaceX website.)
I don't know the specifics of what SpaceX is doing, but on other
launchers, I've heard of helium being used to maintain the pressure in
fuel tanks. Helium is inert and lighter than all other gases, except
for hydrogen.
Skipping some questions.
> 5) How are the Merlin engines made to be sea-water proof? Would
keeping them
> pressurized with O2 only be a good idea to keep out the seawater? Or would
> that likely cause the engines to ice over? Of course ice over of the engines
> would improve overall buoyancy and help keep liquid seawater out. Interesting.
Actually, from memory, salt water immersion has been tested with other
liquid fueled rocket engines and it's not the huge issue that you'd
think it might be. Certainly you have to take care that the salt water
doesn't get into the electronics, but for the engine itself, the key
seems to be prompt recovery and rinsing off all of the salt water.
Besides, every vehicle launched from KSC spends some time in the
relatively salty air. A short dunk in salt water shouldn't be much
worse.
Jeff
--
" Solids are a branch of fireworks, not rocketry. :-) :-) ", Henry
Spencer 1/28/2011